Communication networks are used in a variety of applications including telephone and computer systems, weapons systems, navigational systems, and advanced control systems in cars, aircraft and other complex systems. Given the variety of applications, many kinds of communications networks have been developed over the years. One common characteristic of communication networks is the use of a communication medium that interconnects various nodes on the network. Various topologies and protocols have been developed to control communications between the nodes of these networks.
One type of network is referred to as Time Division Multiple Access (TDMA). In a TDMA network, nodes in the network are assigned time slots for communicating over the network. Many different TDMA protocols have been developed for communication between nodes of a network. For example, these protocols include TTP/C, SAFEbus, FlexRay and other TDMA protocols.
In many time-triggered protocols, such as the TTP/C Specification, a guardian is used to monitor messages to prevent faulty messages from propagating through the network. Left unchecked, the nodes producing faulty transmissions can interfere with the ability of the other nodes to properly start up the network and bring it from an unsynchronized state to a synchronized state. The guardian often monitors messages to assure that transmission characteristics, including but not limited to, transmission rate and order, are acceptable. Through the guardian's analysis of the content of the frames, faulty transmissions are detected so as to limit their influence on network start up and operation. Unfortunately, due to the complexity of the communication system and protocol, the guardian is a complex component of the hub and typically requires a significant amount of hardware, software and testing to implement and maintain. This adds expense to the design and operation of a network with a central guardian.
Therefore, a need exists for a simpler mechanism for reducing the impact of faulty transmissions on network start up.